JPH0265866A - Apparatus and method for plasma treatment of small diameter tube - Google Patents

Abstract

PURPOSE: To enable to plasma-process the inside wall of a bore by limiting a plasma generation within a plasma area between electrodes covered by a dielectric which substantially prevents all of plasma generation outside the plasma area. CONSTITUTION: Electrodes 58 are tightly fit in a cavity 50 so as to be in contact with one or more tubes in one or more bores 52, and the electrodes 58 are entirely covered by a dielectric 42. To plasma-process the inside wall of a small-diameter tube 54, it is recommended to keep a pressure difference between the near end 55 and the far end 56 of the tube 54, however, it is not always required. It is recommended that the pressure difference is small enough to generate a consistent plasma between the both ends of the tube as well as large enough to purge a gas component from the tube resulting from a process gas through the tube.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to methods and devices for facilitating the attachment of cells to surfaces. More particularly, the present invention relates to an apparatus for plasma treating the lumen wall of a small diameter tube in preparation for cell deposition.

BACKGROUND OF THE INVENTION Over the past three decades, tubular grafts have been extensively employed to restore blood flow to ischemic areas, to provide blood flow to hemodialysis patients, and to repair aneurysms. Ta. Although this type of treatment is generally successful initially,
The long-term prognosis for patients receiving small-diameter grafts is unsatisfactory. This is primarily because grafts smaller than 4 can become occluded over time due to the thrombogenicity of the graft material.

Much research has been conducted to find blood compatible materials for use in vascular grafts and other biomedical devices. Although synthetic plastics are the preferred materials, even plastics such as polytetrafluoroethylene and silicone rubber, which are more compatible with blood than most plastics, are still thrombogenic.

Thrombogenicity and occlusion problems are even more severe with small diameter grafts. Van Barahem (Van W
achem) et al. Biomaterigls 6.

403 (1985), 4II! Although clinical successes have been reported using polymeric grafts with I11 or higher, grafts with I11 or higher generally gave unsatisfactory clinical results because they occluded readily. Similarly, Baker et al.
merican Journal of Surgery
y 15O-197 (1985), states that long-term patency of large-diameter tube grafts is relatively acceptable, whereas small-diameter (5 mm or less) grafts exhibit poor long-term patency rates.

It has long been thought that the ideal fluid-surface interface is the natural human endothelium, and much of the recent research has been directed toward endothelialization treatments. For example, Be1den et al. reported that the patency rate after inoculating endothelial cells into a polyester vascular graft with an inner diameter of 40 mm and transplanting it into a dog was
Trans-Am, Soc, Artif.

Intern,○r ans, 28.173(198
2) is discussed.

Annals of Jarrell et al.
Surgery-203, 671 (1986) states that endothelial cells coated with platelet-rich plasma on polyester
It has been described that a high degree of firm adhesion was observed at 0 min, on amnion/collagen coated polyester at 60 min, and at 2 h on plain polyester, but only the amnion/collagen coated surface showed complete graft coverage. ing.

It is well known to modify polymer surfaces by treatment with various plasmas to achieve various purposes. ”
The term "plasma" is commonly used to describe an ionized gaseous state.

Plasmas consist of high-energy positively or negatively charged ions, negatively charged electrons, and neutral atomic species. As is known in the art, plasma is a combustion-fire;
It can occur by physical impact or, very often, by electrical discharges, such as corona discharges or glow discharges. In the case of radio frequency (RF) discharges, the substrate to be treated is placed in a vacuum chamber and a low pressure gas is introduced into the system. The gas undergoes an It,F discharge (capacitive or inductive) 2 that generates an electromagnetic field.As a result of the absorption of energy from the electromagnetic field, ionization of the gas occurs resulting in high-energy particles that modify the surface of the support. .

The extent of support surface modification by plasma is a function of the number and average energy of particles impacting the surface. The energy of charged particles in a plasma is best defined by the ratio of the electric field strength E to the background gas pressure p (E/p). This ratio is a relative measure of the average energy that an ion or electron can gain between successive scattering collisions with neutral gas molecules. From this ratio it is clear that the energy of the plasma particles can be increased by increasing the electric field strength or decreasing the gas pressure.

The strength of the electric field can be increased by increasing the power of the discharge, but this is accompanied by additional heat generation. On the other hand,
If the gas pressure is lowered too much, there will not be enough molecules for ionization.

Plasmas have been used to alter the wettability of a surface, its electrostatic properties, and its receptivity to the deposition of a layer of adhesion polymeric material. Japanese Patent No. 122.529 discloses that the tube is placed in an insulating system, the inner surface of the tube is activated with plasma generated by induction, and the surface is prepared for graft polymerization by applying a polymerizable monomer to the surface. It has been shown that

Van Varachem et al. (supra) show that endothelial cells can be cultured on glass or glow discharge treated polystyrene.

Garf 1nkle et al.
ns.

Am-Sac, Artif, Intern, O
rgans, 30.

432 (1984) demonstrate the plasma spraying of a fluorocarbon polymer coating onto the luminal surface of a porous polyester graft having an internal diameter of 4-5H.

In this article, an induced plasma generated outside the graft penetrates the lumen by penetrating the pores of the graft. Significantly improved patency has been reported for treated grafts.

Published European patent application EP 89-124A discloses that the inner surface of a plastic tube with an inner diameter of 3.5 mm is placed inside an insulating second tube and that the electrodes are placed outside the insulating tube. It has been shown that plasma treatment is possible.

(Problem to be Solved by the Invention) Despite extensive research into anti-thrombotic prostheses, the problem of thrombogenicity has not been satisfactorily solved for grafts with a diameter smaller than 1%. do not have. The present invention aims to solve this problem.

SUMMARY OF THE INVENTION An apparatus for whole-plasma reforming of the interior surface of an article includes an electromagnetic field generator disposed within a housing. The housing is connected to a reduced pressure source and a gas delivery assembly. The generator is connected to the RF mains supply and is encapsulated in a dielectric in all directions except in the direction of the plasma zone adjacent to the generator. The plasma zone receives articles to be plasma treated.

In one preferred device of the invention, the housing is a canister with an upper chamber and a lower chamber separated by a diaphragm, the gas inlet pipe connecting to the upper chamber and the vacuum connection connecting to the lower chamber. It will be done. A preferred generator includes a plurality of parallel grate electrodes.

The dielectric is a polymer f with a depression inside to receive an electrode.
a It is a block of polyolefin. A bore containing the plasma zone penetrates the dielectric and establishes a gas passage from the upper chamber through the recess and the diaphragm opening to the lower chamber. A tube to be plasma treated is placed within the bore and extends from the upper chamber to the lower chamber.

A conduit through the septum provides gas communication between the upper and lower chambers. This conduit controls the flow of gas from the upper chamber to the lower chamber such that a lower gas pressure is maintained in the lower chamber. A rod passes through the top wall of the canister and hooks the top end of the tube to be plasma treated, allowing the long tube to be drawn gradually through the plasma zone between the electrodes.

In another preferred form of the device, a tube is placed between support rails and a dielectric with electrodes placed therein is pulled laterally along the rails to apply a plasma across the lumen wall of the long tube.

In another aspect of the invention, a method of applying a plasma to the inner wall of an article includes placing the article within the plasma zone of the apparatus of the invention, evacuating the chamber, and introducing gas into the chamber.
Then, apply full power to the electrode. An electromagnetic field is created that penetrates the walls of the article, which ionizes the gas inside the article and generates a plasma, which treats the interior walls of the article. In a preferred method, the lumen wall of the tube is treated by drawing the tube through a plasma zone.

An alternative method of the invention consists in holding the tube stationary between support rails and moving the dielectric with the electrodes disposed therein from one end of the tube to the other along the rails.

According to the invention, the dielectric shields the electrodes on all sides except the facing faces, so that a capacitively coupled plasma discharge occurs only in the plasma zone between the electrodes. This manner allows one or more tubes to be treated simultaneously, all of which receive an intense plasma generated at relatively low power levels. The reason only low power is required is that any external discharges that would dissipate power are prevented. The low power required to generate the plasma prevents heat build-up that can cause thermal losses in low softening point polymeric materials. By controlling the pressure difference from one end of the tube to the other - the plasma is generated uniformly in the plasma zone between the electrodes, which allows long tubes with internal diameters (ID) of the order of 2.51 or even smaller. The lumen surface is uniformly modified.

Let's briefly talk about the drawings.

FIG. 1 is a perspective view of a preferred plasma generating device of the present invention.

FIG. 2 is a vertical cross-sectional view of the device of FIG. 1 taken along line 2--2.

6 is a horizontal cross-sectional view taken along line 6--5 of the apparatus of FIG. 1; FIG.

4 is an enlarged cross-sectional view of the preferred gas flow control portion of the apparatus of FIG. 2; FIG.

FIG. 5 is an exploded view showing the structure for opening and closing the device of FIG.

6 and 7 are partial vertical cross-sectional views of the device of FIG. 1, showing other structures for opening the device.

8a is a horizontal cross-sectional view taken along line 8--8 of the apparatus of FIG. 1; FIG.

Figure 8b is a horizontal cross-sectional view similar to Figure 8a, but showing an alternative structure for opening and closing the device.

FIG. 9 is a partial vertical cross-sectional view taken along line 2--2 of an alternative version of the apparatus of FIG. 1, showing an alternative structure for withdrawing the tubes to be processed within the plasma zone.

FIG. 10 is a partial vertical cross-sectional view taken along line 2--2 of the apparatus of FIG. 1, showing the elongated tube ready for plasma treatment.

FIG. 11 is a vertical cross-sectional view taken along line 2--2 of the apparatus of FIG. 1, illustrating a simplified apparatus for full tube processing in a static state.

12 and 16 are partial vertical cross-sectional views taken along line 2--2 of the apparatus of FIG. 1, showing tubes arranged for treatment by an alternative form of the generator-dielectric portion of the apparatus of the invention; shows.

FIG. 14 is a perspective view of a preferred apparatus of the present invention for generating plasma in a long tube.

FIG. 15 is a vertical cross-sectional view of the device taken along line 15--15 of FIG. 14.

While the invention may take many forms, preferred forms thereof will now be described in detail.

This description, however, is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the form shown and described. The scope of the invention will be defined by the following claims and their equivalents.

Typically, the plasma discharge produced by parallel plate electrodes is directed over the entire area surrounding the electrodes. The device of the invention prevents any substantial discharge other than that occurring within the tube in the plasma zone between the electrodes. Since the power applied to the electrodes is not wasted as an external plasma discharge, the lumen wall of the tube located within the plasma zone is subjected to an intense plasma.

According to the invention, glow discharge is preferred. This is because this is essentially a "cold" plasma. The preferred device capacitively generates a glow discharge plasma between parallel plate electrodes. The resulting plasma is homogeneous and easily controllable, thus covering the small diameter tube lumen wall uniformly. Multiple tubes can be processed at once, so the device can be used for at least semi-automatic tube processing.

Referring to the drawings, Figures 1 and 2 include a plasma generating apparatus 10 of the present invention including a canister 12ii with an upper chamber 14 having sidewalls 15 and a lower chamber 16 having sidewalls 17. Chambers 14 and 16 are
They are separated by a diaphragm 18 having an opening 19 therethrough. The upper chamber 14 is provided with a door 20 by which the interior of the chamber can be reached and which can be sealed when the device is evacuated as described below.

An opening 22 passes through the upper wall 21 of the upper chamber 14 . A rod 23 having a handle 24 for grasping is inserted into the opening 22.
It projects into the upper chamber 14 in a slidable manner in a sealed manner all the way through.

Gas inlet 26 includes a valve 28 and a tube 50 adapted to connect to a gas source (not shown), which may be a single gas or a conventional gas source prior to entering tube 50. The gas mixture is mixed in the device.The inlet pipe 32 connects the valve 28 and the upper channel (-14) and passes through the inlet 64 of the upper wall 21.

A coaxial cable 36 passes through the sidewall 15 and connects to an R,P power source (not shown).A nozzle 68 is secured to the lower chamber 16 and connects to a vacuum source (not shown).
It has been adjusted to connect to Pressure gauges 40 and 41 are connected to upper chamber 14 and lower chamber 16, respectively.
It is connected to the.

As best seen in FIG. 2, the dielectric 42 supported on the diaphragm 18 consists of two blocks 46 and 4 of high molecular weight plastic, such as polyethylene, joined face-to-face.
4 is preferred.

Recesses 45 and 46 are arranged inside blocks 46 and 44. For example, recesses 45 and 46 can be machined from blocks 46 and 44, or the blocks can be shaped to include the recesses. Blocks 46 and 44 also define spines 47 and 48, so that when blocks 46 and 44 are joined face-to-face, recesses 45 and 46 mate to form cavity 50.
The grooves 47 and 48 meet to form the cavity 5.
A bore 52 passing through the hole 52 is formed.

Bore 52 was snug. However, it is a sliding fit.
ing fit ), the plastic tube 54 to be plasma treated is received. Tube 54 has a proximal end 55 and a distal end 56.

Two electrodes 58 are placed in recesses 45 and 46 in a snug pressure fit. The depth of the recess is such that when the electrode 58 is placed in place within the recess, the electrode is adjacent to the tube 54 and defines the plasma zone as a portion of the bore 52 between the electrodes. A coaxial cable 66 conducts power from the FtF power source to electrode 58.

A rod 26 having an inner end 59 extends through the opening 22 and into the upper chamber 14 . Preferably at the inner end 59 of rod 26, preferably at the proximal end 55 of tube 54.
There is a hook 60 adjusted to engage an eye 61 attached to the.

Air flow restriction conduit 64 provides gas communication between upper chamber 14 and lower chamber 16 through diaphragm 18, as described in more detail below.

Dielectric 42, plastic tube 54 and electrode 58
The details of the relationship are shown in FIG. Electrode 58 is in cavity 5
0, and one or more bores 52
The electrodes are shown placed in contact with one or more tubes within the tube, with the electrodes completely shielded by dielectric 42.

When plasma treating the lumen wall of small diameter tube 54 in accordance with the present invention, it is preferred, but not necessary, to maintain a pressure differential between proximal end 55 and distal end 56 of tube 55. This pressure difference is small enough to generate a uniform plasma at both ends of the tube, but small enough to create a flow of process gas through the tube, which purges the generated gas components from the tube. Larger is preferable. Generally, for any combination of plasma parameters, if a pressure difference of about 0-60%, preferably about 10 factors, is maintained between the tube ends 55 and 56, a uniform plasma in the plasma zone will be obtained. Thus, for example, if the gas pressure at proximal end 55 is 14.0 Torr, the preferred pressure at distal end 56 is about 12.6 Torr.

The pressure difference between proximal end 55 and distal end 56 was monitored by pressure gauges 40 and 41 in upper and lower chambers 14 and 16, respectively, with full control of gas flow from inlet 26 and exhaust from nozzle 68. It will be clear to those skilled in the art that the scale can be achieved by A preferred structure for providing and maintaining the desired pressure differential is a gas flow restriction conduit 64, as shown in FIG. conduit 6
4 penetrates the diaphragm 18 from the upper chamber 14 to the lower chamber 16 and serves to restrict the flow of gas between these chambers.

For certain applications of the plasma generator of the present invention,
The preferred pressure difference between each chamber may be other than a factor of 10. FIG. 4 shows a preferred means of adjusting this ratio by simply inserting a sleeve 66 inside the conduit 64. The sleeve 66 may have any wall thickness, thereby allowing adjustment of the ratio without changing the v conduit 64 itself.

As mentioned above, this device has structure for accessing the interior of the canister. One suitable structure is shown as door 20 in FIGS. 1 and 5. Figure 5 shows the upper chamber 14.
The door 20 is shown fitting into the open lower 0 of the side wall 15 of . door 2
0 is preferably provided with pegs 72 at each corner, these are attached to the side wall 1
5, the beg serves to position the door 20 on the open lower door 0. O-rings 76 in grooves 78 in sidewall 15 form a seal with door 20 when vacuum is applied through nozzle 68.

Figures 6 to 8 show a canister 12 instead of the door in Figure 5.
Shows the structure for opening. (In the following discussion of the alternative embodiments of the invention, elements corresponding to those described above with respect to the apparatus of FIG. 1 will be referred to in FIG. The bottom surface 81 of the lower chamber 16Δ is provided with an opening 82 and a thread 86 on the inner surface of the surface 81. A groove 84 in the bottom surface 81 receives an O-U puffer 85. A cover plate 86 has a screw thread that engages the thread 83. The upper surface 88 of the cover plate 86 has a ridge 87 which seals the top surface 88 of the cover plate 86 into the O-ring 85 .

As shown in FIG. 7, one chamber 14b and 16b has side walls 15b and 17. removably secured and sealed by interlocking threads 90 and 92 on b. Any of the usual means for sealing threaded joints.

For example, grease can be used.

The upper chamber and lower chamber can be separated. FIG. 8a shows the side wall 17c of the lower chamber 16c with a flat top surface 104.

FIG. 8b shows O-ring 100 within groove 102 of flat surface 104. FIG. The O-ring 100 sealingly fits against the lower surface of the side wall of the upper chamber when vacuum is applied through the nozzle 38.

Structures other than the hook 60 and eye 61 shown in FIG. 2 (not shown) may be used to secure rod 23 to tube 54. For example, the inner end 59 of rod 26 and the proximal end 55 of tube 54 can be secured with a clamp or simply tied together with a cord or wire. Alternatively, a small magnet inserted by a push fit into the proximal end 55 of the tube 54 can be inserted into the inner end 59 of the rod 23.
will trap pieces of magnetic material attached to it.

An alternative version of the invention, shown in FIG. 9, also employs magnetic forces to pull the tube within the plasma zone, while also being a potential source of leakage. The sliding seal between rod 23 and top wall 21 in FIG. 2 is removed. In FIG. 9, a preferably narrow glass casing 110 with one closed end 111fc is permanently sealed into an opening 22a in top wall 21d. A rod 113, preferably made of a magnetic material, a crow bearing a magnetic band, or other magnetic material, is slidably disposed within the casing 110. The distal end 114 of rod 115 is attached to proximal end 55d of tube 54d by suitable means as described above.

Magnet 115'f: When placed on the outer wall 116 of the casing 110, the rod 116 can slide upwardly within the casing 110 and bow the tube 54d with it.

Tubes 54 of any length can be processed by the apparatus and method of the present invention. From Figure 2, distal end 5
It can be seen that 6 is the end of the coiled tube 54 located within the lower chamber 16. FIG. 10 shows a coil 120 of tube 54e having a distal end 56e. Preferably, the coil 120 has a gas tube 54e.
A plurality of holes 122 are provided at approximately 1 meter intervals to assist in penetrating the hole. For this form of the invention.

It has been found that hole 122 preferably has a diameter substantially equal to the inner diameter of tube 54e. When the coil 120 is subjected to plasma treatment, a canister shown in FIG.
It is convenient to adopt the form of

For some types of plasma processing, a simplified apparatus as shown in FIG. 11 may be appropriate. FIG. 11 appears to be similar to the device of FIGS. 1 and 2, except that it includes septum 18, conduit 64. Pressure gauges 40 and 41. Also, there is no structure for withdrawing the tube within the plasma zone. In FIG. 11, a plasma generator 10f includes a canister 12f having a dielectric 42f supported by an internal circumferential rim 160. Dielectric 42f consists of blocks 43f and 44f with indentations 45f and 46f defining a cavity 50f. Grooves 47f and 4
8f is mated with a bore 52f that receives a tube 54f.
form. Electrodes 58f are disposed within depressions 45f and 46f.

A plasma zone is defined in the bore 52f between them.

FIG. 12 shows a plurality of annular electrodes 164 surrounding tube 54g within dielectric 42g. Lead wire 166 connects electrode 164 to a power source (not shown). Electrode 1
34 are spaced about 1-10 cm, preferably about 2-5 crIL.

Although capacitively generated plasma between parallel plate electrodes is preferred, inductively generated plasma can also be used to treat luminal surfaces in accordance with the present invention. Figure 16 shows an arrangement suitable for this form of the invention. Coil 14 with leads 142 connected to a power source (not shown)
0 wraps around tube 54h and completely dielectric 42h
is housed in.

Still other arrangements of the elements of the inventive generator for plasma treatment of a tube lumen with dielectric-shielded electrodes are also contemplated. For example, a stationary tube can be placed adjacent an electrode housed within a dielectric and the electrode-dielectric unit can be moved relative to the tube to generate a plasma within the tube lumen.

Figures 14 and 15 illustrate a configuration of the plasma generator of the present invention that includes a mobile electrode-dielectric assembly that is particularly suitable for plasma treating the lumen walls of long tubes.

Preferably, the configurations shown in these figures are arranged substantially horizontally.

The plasma generator 200 includes a proximal end plate 204.
- a preferably cylindrical housing 202 having a distal end plate 203 and side walls 208; Housing 202 may be of any suitable material, such as metal, ceramic, plastic, or glass, although a preferred glass or transparent plastic is shown in FIG. 14 to facilitate viewing of the relationships of the internal components.

Housing 202 has a hole 21 that receives tube 218.
The proximal chamber 210 and the distal chamber 212 are separated by a septum 214 having a diameter of 6. Gas flow restriction conduit 220 and optional sleeve are provided for conduit 64 as previously described.

Gas communication is provided through diaphragm 214.

End plate 204 and septum 214 are hermetically fitted to sidewall 208 by any suitable means, preferably by O-IJ ringing (not shown). End plate 206 is also sealingly fitted to sidewall 208, but is preferably integral with the sidewall.

A gas delivery tube 222 and a pressure gauge 223 extend through distal end plate 206. Decompression nozzle 224 and pressure gauge 2
25 passes through proximal end plate 204. These all form airtight seals with their respective end plates.

An electrode-dielectric assembly 1)-230 is removably disposed within the distal chamber 212. This is electrode 2
61, dielectric 262. upper tube support rail 264,
Lower tube support rail 266° includes distal clamp 268 and proximal clamp 240. A coaxial cable 242 sealingly passes through a hole 244 in distal end plate 206 to deliver RF power to the electrodes. A magnet 246 is secured to dielectric 262 by any suitable means, such as an adhesive.

As shown in FIG. 15, electrode 261 fits snugly into cavity 248 as described above with respect to electrode 58.

Tube 218 is positioned between upper rail 234 and lower rail 236 in the plasma zone adjacent electrode 231 . Assembly IJ-230 has tube 21 as described below.
8 is adjusted to be inserted and removed from the housing 202.

All forms of the device of the invention described above may employ conventional high frequency RF generators and impedance matching networks and conventional vacuum systems. Devices of this type are well known in the art (e.g., U.S. Pat.
No. 844,652]1 Details regarding these aspects of the invention are not necessary for a complete understanding of the invention.

When preparing generator 10 for use, canister 12 is opened and tube 54 to be plasma treated is inserted into pore 52 so that it occupies the plasma zone between electrodes 58. Eye 61 is attached to proximal end 55 of the tube by any suitable means. Engage the hook 0 on the inner end 59 of the rod 23 with the eye 61 and attach the canister 1.
Seal 0.

Insertion of the tube into the generator 200 is performed as follows. Remove proximal end plate 204 and septum 214 from housing 202 - slide assembly 230 forward until completely removed from housing 202. Open and remove clamps 268 and 240 and slide upper and lower rails 264 and 266 until they are released. The rails are then separated and the tube 218 to be plasma treated is placed between them. The generator is then reassembled by reversing these steps.

To plasma treat the tube, load it.

The assembled generator 10 or 200 is evacuated by connecting a vacuum nozzle to a vacuum pump. Gas from a gas supply source is introduced into a device consisting of a gas inlet tube until a desired gas pressure difference is achieved across the conduit. If it is desired to reduce the diameter of the conduit as described above, one or more sleeves 7 can be inserted into the conduit. By applying a current at the desired frequency from the RF generator to the electrodes,
An RF electromagnetic field is generated within the plasma zone. Ionization of the gas within the tube is induced by the electromagnetic field, and the plasma generated within the tube modifies the lumen wall of the tube in the portion within the plasma zone.

If it is desired to plasma treat a tube of length equal to or less than the length of the electrode, it may be preferable to use the apparatus of FIG. 11. If the length of the treated plow tube is longer than the length of the electrode, the entire tube can be treated with the apparatus of FIG. 10, or preferably with the apparatus of FIG. 14. An external magnet (not shown in FIG. 14) is placed on the outside of sidewall 208, directly above magnet 246. These two magnets are thereby magnetically interlocked, so that by moving the external magnet laterally along the sidewall, the dielectric-electrode unit can be moved in either direction along the rail, as shown by the arrows in FIG. It also slips. Determination of the appropriate speed for withdrawing the tube of FIG. 10 or the electrode-dielectric unit of FIG. 14 to obtain the desired degree of surface modification is within the ability of those skilled in the art. be.

By employing the apparatus and method of the present invention, a lumen surface can be treated with a plasma generated from any gas and under any suitable plasma parameters as determined according to the desired surface treatment. For example, the gas is ammonia.

Nitrogen, neon, argon-xenon-crypt/.

Oxygen or mixtures thereof, but is not intended to be limited thereto. In addition, the gas may be a vaporized organic material, such as an ethylene monomer or a low molecular weight nitrogenoxane to be plasma polymerized or plasma welded on the lumen wall of the tube.1/) Suitable plasma parameters are approximately A power level of 10 to 1000 Watts, an RF frequency of about 1 to 100 MHz, an exposure time of about 5 seconds to 12 hours, a gas pressure of about 0.1 to 100 Torr, and a gas flow rate of about 1 to 200 standard CC/sec. Will.

According to the present method of plasma treating a small diameter tube to modify the lumen wall to prepare it for attachment of endothelial cells, the preferred plasma is produced by the present apparatus.

From ammonia or nitrogen, power level 50-125 watts - RF frequency about 8-60 MHz, exposure time of specific area of tube 0.2-2.0 minutes, gas pressure about 1-2
0 Torr, and a gas flow rate of approximately 5-20 standard engineering/sec.

Dielectrics 42 and 262 may be any material that prevents electric fields from being applied in any direction other than within the plasma zone between the electrodes. Suitable materials are e.g. glass,
Rubbers, ceramics, and preferably polymeric polyolefins such as polypropylene or polyethylene. It has been found that the encapsulation of the electrodes provides sufficient shielding to substantially prevent plasma formation outside the plasma zone.

Suitable electrodes may be any electrically conductive material, but aluminum and stainless steel are preferred. The preferred length is 2-10 CML, but any length that matches the dimensions of the housing is suitable.

Similarly, the width and height of the electrodes are not critical, but preferred electrodes are about 0.1 cm thick and about 0.5 to 2.0 cm wide.
It's a box.

As mentioned above, the housing 202 is made of metal, plastic,
Alternatively, it may preferably be glass.

Those skilled in the art will of course understand that if magnets are used to move the electrodes, the metal housing must be non-ferrous. The tube support rail may also be glass or plastic, preferably plastic with a low friction surface.

Although the apparatus of the present invention has been described in detail for plasma treatment of the lumen of a small diameter tube, it is clear that by simply changing the dimensions of the dielectric and electrodes it could be used to treat any article with no lab coat that could come into contact with the plasma gas. ↓ b0 The article to be plasma treated is a non-conductive material.

For example, it may be made of glass, plastic, ceramic, rubber, or composite materials thereof. Conductive materials-fc, such as metal lab coats, cannot be treated with the apparatus of the invention. This is because electromagnetic fields do not penetrate conductors. A preferred material for the frontal graft is polyurethane. This is because it closely resembles human blood vessels due to its high degree of compliance and flexibility.

(Effects of the Invention) As described above, the device of the present invention generates plasma in the lumen of a tube with an inner diameter of about 2.5 wpr or less. By restricting the plasma generation to only the plasma zone, no power is wasted and therefore no power is generated inside the tube within the plasma zone without giving too much power to the electrodes. A targeted plasma is generated, which minimizes heat buildup and allows plasma treatment of the lumen walls of tubes made of heat-sensitive materials.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a preferred plasma generating device of the present invention. FIG. 2 is a vertical cross-sectional view of the device of FIG. 1 taken along line 2--2. FIG. 3 is a horizontal cross-sectional view of the device of FIG. 1 taken along line 6--3. 4 is an enlarged cross-sectional view of the preferred gas flow control portion of the apparatus of FIG. 2; FIG. FIG. 5 is a developed view showing the structure for opening and closing the charge of FIG. 1. 6 and 7 are partial vertical cross-sectional views of the device of FIG. 1, showing alternative structures for opening the device. 84 is a horizontal cross-sectional view taken along line 8--8 of the apparatus of FIG. 1; FIG. Figure 8b is a horizontal cross-sectional view similar to Figure 8a, but showing an alternative structure for opening and closing the device. FIG. 9 is a partial vertical cross-sectional view taken along line 2--2 of an alternative version of the apparatus of FIG. 1, showing an alternative structure for withdrawing the tubes to be processed within the plasma zone. FIG. 10 is a partial vertical cross-sectional view taken along line 2--2 of the apparatus of FIG. 1, showing a long tube ready for plasma treatment. FIG. 11 is a vertical cross-sectional view taken along line 2--2 of the apparatus of FIG. 1, illustrating a simplified apparatus for processing tubes in a static state. 12 and 16 are partial vertical cross-sectional views taken along gland 2-2 of the device of FIG. shows. FIG. 14 is a perspective view of a preferred apparatus of the present invention for generating plasma in a long tube. FIG. 15 is a vertical cross-sectional view of the device taken along line 15--15 of FIG. 14. In each figure, the symbols represent the following: 10: Plasma generator 12: Canister-14, 1
6: Chamber 18: Diaphragm 19.22: Opening
20 Nido Ac 1: Upper wall 26: Rod 24: Handle 26: Gas inlet part 28: Valve
30: Gas inlet pipe 62: Gas inlet pipe
64: Gas inlet 36 twin coaxial cable 38: Nozzle 40.41: Pressure gauge 42 (45, 44
) : Dielectric 45.46 : < Hollow 47,48
: Groove 50: Capacity 52: Bore 54: Tube 58: Electrode 60: Hook 61: Eye 64: Conduit (gas) 66: Three foot 0: Opening 72: Peg 74 Nislot 76.85: O-ring 78.102: Groove 81 : Bottom surface 83.87
, 90, 92: Screw thread 84: Groove 80: Cover plate 110 Nigarasu casing 113: Rod (@
115: Magnet 116: External wall
120: Coil (tube) 122:
Hole 130: Circumferential rim 164: Annular electrode
136, 142: Lead wire 140: Coil
200: Plasma generator 202: Housing 204, 206 Freezing plate 208: Side wall
210, 212: Chamber 214 = Diaphragm
218: Teufu 220: Conduit (gas)
222: Gas feed pipe 223.225: Pressure gauge
224: Decompression nozzle 230: Electrode (231)-dielectric (232) assembly 234.236: Rail
238, 240: Clamp 242: Coaxial cable
244: Hole 246: Magnet 248: Cavity (outer 4) F/G-7 F/G-6 IG-8a F/G-/3

Claims (1)

Claims: 1. a) a housing having first and second chambers separated by a diaphragm defining an opening for receiving an article to be plasma treated; b) a bore within the first chamber therethrough; a dielectric, the bore comprising a cavity within the dielectric for receiving an article and a plasma zone; c) disposed within the cavity and directed by the dielectric in all directions other than the direction of the plasma zone; an electrode enclosed and defining a plasma zone; d) means for opening and sealing the housing; e) means for applying power to the electrode; f) means for communicating gas to the first chamber; and g) Apparatus for applying a plasma to the inner wall of a plastic article, comprising means for connecting the second chamber to a source of reduced pressure. 2. The apparatus of claim 1, further comprising means for maintaining a pressure differential between the first and second chambers. 3. Further, penetrating the upper wall of the housing in a sealed state;
2. Apparatus according to claim 1, comprising takeoff means for taking off the article within the plasma zone. 4. further including an article support rail passing through the bore;
2. The apparatus of claim 1, wherein the dielectric is slidably mounted on the rail. 5. a) a housing enclosing a chamber; b) shielding means in said chamber having a bore therethrough, said bore comprising a cavity for receiving the article to be plasma treated and a plasma zone; c) a) means for generating an electromagnetic field within said cavity surrounded by shielding means in all directions other than the direction of the plasma zone; d) means for opening and sealing the housing; e) means for energizing said generating means; Apparatus for applying a plasma to the internal walls of a non-conductive article, comprising: means for applying; f) means for communicating a gas into the chamber; and g) means for connecting the chamber to a source of reduced pressure. 6. a) a canister having a side wall, a top wall and a septum, the septum dividing the canister into an upper chamber and a lower chamber and defining an opening; b) a dielectric in the upper chamber, The dielectric has a bore therethrough, the bore communicating the upper chamber and the lower chamber through the opening, and the bore defining a cavity and a plasma zone within the dielectric for receiving the tube to be plasma treated. c) a plurality of electrodes disposed within the cavity and surrounded by a dielectric in all directions except the direction of the plasma zone, defining a plasma zone therebetween; d) means for opening and sealing the canister; e) a conduit passing through the diaphragm for maintaining a pressure difference between the upper and lower chambers; f) take-off means sealingly passing through the top wall; g) means for applying power to the electrodes; h) A device for applying a plasma to the lumen wall of the plastic tube, consisting of an inlet assembly for introducing gas into the upper chamber; and i) a nozzle for connecting the lower chamber to a source of reduced pressure. 7. a) a first chamber and a second chamber separated by a diaphragm defining an opening for receiving the tube to be plasma treated;
a first end plate removably attached to the housing and defining a first chamber; and a second end plate removably attached to the housing and defining a second chamber.
a housing having an end plate; b) a dielectric within a first chamber, the dielectric having a bore therethrough for receiving a tube and a cavity within the dielectric; c) a plurality of electrodes disposed within said cavity and surrounded by a dielectric material in all directions except the direction of the plasma zone, defining a plasma zone therebetween; d) within said first chamber and comprising said plasma zone; mated upper and lower support rails for tubes passing through the bore, with the dielectric slidably mounted on these rails; e) removable upper and lower rails; f) a conduit through the diaphragm for maintaining a pressure difference between the first and second chambers; g) means for moving the dielectric on the rail; h) an electrode. means for applying electrical power; i) a delivery assembly for introducing gas into the first chamber; and j) a nozzle for connecting the first chamber to a source of reduced pressure; A device for applying 8. a) placing a tube in a plasma zone adjacent to a plurality of electrodes, the electrodes being housed within a dielectric in a housing enclosing the chamber; b) evacuating the chamber; c) evacuating the gas. into the chamber, such that the gas contacts the tube lumen wall; and d) applying radio frequency power to the electrode, which creates an electromagnetic field that causes the gas in contact with the lumen wall to A method of treating a lumen wall of a tube with a plasma, the method comprising ionizing the lumen wall of a tube, producing a plasma due to the ionization, and treating the lumen wall with the plasma. 9. The method of claim 8 further comprising withdrawing the tube within the plasma zone. 10. The method of claim 8, further comprising moving the dielectric containing the electrodes within the plasma zone relative to the tube.